RO membrane flow restrictor

Kernel Panic · 12/10/2006, 04:56 PM

Ok, so I made the mistake of buying a ro/di unit with the 100 gpd membrane before I discovered that it has a lower rejection percentage than the 75 gpd membrane.

I am switching to the 75 gpd membrane. I have read conflicting information on the right size flow restrictor. Some sites say 550 ml/min, some either 550 or 800 ml/min, and some recommend 800 ml/min. Which is correct? Furthermore, is it going to make that much difference when my tap tds is only 30ppm?

I have the 800 ml/min restrictor.

RandyStacyE · 12/10/2006, 05:12 PM

www.thefilterguys.biz sell some restrictors listed as follows:
100 gpd - 850

75 gpd - 550

http://www.thefilterguys.biz/ro_membranes.htm

AZDesertRat · 12/10/2006, 06:08 PM

I used a 750mL restrictor on my 75 GPD for years and it worked great. It made my waste ratio closer to 6:1 but it extended the life of the membrane due to better flushing. It also depends on your water temperature, if its cold you may want a smaller one or better yet get an adjustable one so you can tune it to exactly 4:1 and adjust for seasonal temperature changes.

Thefilterguys · 12/10/2006, 11:19 PM

Filmtec 75 GPD membranes are rated for a 4:1 flow which is what you will get from a 550 ml restrictor. They only cost $6 and are well worth the money. We see a great number of people with adjustable restrictors and their systems are all out of wack because they have them adjusted wrong.

Jim

DrBDC · 12/11/2006, 06:34 AM

Where are those restrictors located at?

Roland Jacques · 12/11/2006, 07:49 AM

Quote:

Originally posted by DrBDC
Where are those restrictors located at?

on the waste water line after the membrane.

Thefilterguys · 12/11/2006, 09:44 AM

Let me know if this helps.

Jim

DrBDC · 12/11/2006, 10:11 AM

So that little plastic tube restrictor is located inside of that housing labeled "C"?

Thefilterguys · 12/11/2006, 11:06 AM

I think you are referring to the plastic tadpole like restrictor which would be located at B inside the tubing. The flow restrictor C has quick fittings on each end and is self contained.

Jim

Kernel Panic · 12/11/2006, 11:48 AM

Quote:

Originally posted by Thefilterguys
Filmtec 75 GPD membranes are rated for a 4:1 flow which is what you will get from a 550 ml restrictor. They only cost $6 and are well worth the money. We see a great number of people with adjustable restrictors and their systems are all out of wack because they have them adjusted wrong.

Jim

Jim, Thanks for responding. Does the above assume an input pressure of 50psi at which the membrane is rated? My membrane sees an input pressure of about 35psi.

Thefilterguys · 12/11/2006, 07:20 PM

50 psi is the minimum pressure a Filmtec should be operating at lower then that they will not be performing properly. All other membranes are rated for 60 psi and above. At 35 psi you are in need of a booster pump without question.

Jim

12/10/2006, 04:56 PM	#1
Kernel Panic Registered Member Join Date: Jan 2006 Location: Canton, GA Posts: 140	RO membrane flow restrictor Ok, so I made the mistake of buying a ro/di unit with the 100 gpd membrane before I discovered that it has a lower rejection percentage than the 75 gpd membrane. I am switching to the 75 gpd membrane. I have read conflicting information on the right size flow restrictor. Some sites say 550 ml/min, some either 550 or 800 ml/min, and some recommend 800 ml/min. Which is correct? Furthermore, is it going to make that much difference when my tap tds is only 30ppm? I have the 800 ml/min restrictor.

12/10/2006, 11:19 PM	#4
Thefilterguys RC Sponsor Join Date: Aug 2006 Location: Duluth, Mn Posts: 553	Filmtec 75 GPD membranes are rated for a 4:1 flow which is what you will get from a 550 ml restrictor. They only cost $6 and are well worth the money. We see a great number of people with adjustable restrictors and their systems are all out of wack because they have them adjusted wrong. Jim __________________ RO/DI Supplies & parts www.thefilterguys.biz We Custom Build Each System Phone 218 724-8000 Current Tank Info: 40 OCEANIC STRETCH HEX FRESH HEAVY PLANTED, 58 OCEANIC LPS, Monti’s ,Softy’s, 18 Nano Zoo’s , 11 Nano, 70 OCEANIC SPS New 200 Cube on the way

12/11/2006, 06:34 AM	#5
DrBDC Registered Member Join Date: Aug 2004 Location: Ballwin, Missouri Posts: 10,358	Where are those restrictors located at? __________________ Some drink at the fountain of knowledge, some just gargle, but most are rabid. Current Tank Info: 180g sps+75 softy/lps on one system tunze's, seio's, mjmods, aquacontroller w/add ons, 2X400 XM10000 and 3X160 vho actinic, 110g sump, 110 frag tank, Geo Beckett and other stuff

12/11/2006, 09:44 AM	#7
Thefilterguys RC Sponsor Join Date: Aug 2006 Location: Duluth, Mn Posts: 553	Let me know if this helps. Jim __________________ RO/DI Supplies & parts www.thefilterguys.biz We Custom Build Each System Phone 218 724-8000 Current Tank Info: 40 OCEANIC STRETCH HEX FRESH HEAVY PLANTED, 58 OCEANIC LPS, Monti’s ,Softy’s, 18 Nano Zoo’s , 11 Nano, 70 OCEANIC SPS New 200 Cube on the way

12/11/2006, 10:11 AM	#8
DrBDC Registered Member Join Date: Aug 2004 Location: Ballwin, Missouri Posts: 10,358	So that little plastic tube restrictor is located inside of that housing labeled "C"? __________________ Some drink at the fountain of knowledge, some just gargle, but most are rabid. Current Tank Info: 180g sps+75 softy/lps on one system tunze's, seio's, mjmods, aquacontroller w/add ons, 2X400 XM10000 and 3X160 vho actinic, 110g sump, 110 frag tank, Geo Beckett and other stuff

12/10/2006, 05:12 PM	#2
RandyStacyE Registered Member Join Date: Nov 2003 Location: Indiana Posts: 2,659	www.thefilterguys.biz sell some restrictors listed as follows: 100 gpd - 850 75 gpd - 550 http://www.thefilterguys.biz/ro_membranes.htm

12/10/2006, 06:08 PM	#3
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	I used a 750mL restrictor on my 75 GPD for years and it worked great. It made my waste ratio closer to 6:1 but it extended the life of the membrane due to better flushing. It also depends on your water temperature, if its cold you may want a smaller one or better yet get an adjustable one so you can tune it to exactly 4:1 and adjust for seasonal temperature changes.

12/11/2006, 11:06 AM	#9
Thefilterguys RC Sponsor Join Date: Aug 2006 Location: Duluth, Mn Posts: 553	I think you are referring to the plastic tadpole like restrictor which would be located at B inside the tubing. The flow restrictor C has quick fittings on each end and is self contained. Jim __________________ RO/DI Supplies & parts www.thefilterguys.biz We Custom Build Each System Phone 218 724-8000 Current Tank Info: 40 OCEANIC STRETCH HEX FRESH HEAVY PLANTED, 58 OCEANIC LPS, Monti’s ,Softy’s, 18 Nano Zoo’s , 11 Nano, 70 OCEANIC SPS New 200 Cube on the way

12/11/2006, 07:20 PM	#11
Thefilterguys RC Sponsor Join Date: Aug 2006 Location: Duluth, Mn Posts: 553	50 psi is the minimum pressure a Filmtec should be operating at lower then that they will not be performing properly. All other membranes are rated for 60 psi and above. At 35 psi you are in need of a booster pump without question. Jim __________________ RO/DI Supplies & parts www.thefilterguys.biz We Custom Build Each System Phone 218 724-8000 Current Tank Info: 40 OCEANIC STRETCH HEX FRESH HEAVY PLANTED, 58 OCEANIC LPS, Monti’s ,Softy’s, 18 Nano Zoo’s , 11 Nano, 70 OCEANIC SPS New 200 Cube on the way